/**
 * base64转文件
 */
export default (dataurl, filename = "elec-sign") => {
  let arr = dataurl.split(",");
  let mime = arr[0].match(/:(.*?);/)[1];
  let suffix = mime.split("/")[1];
  let bstr = atob(arr[1]);
  let n = bstr.length;
  let u8arr = new Uint8Array(n);
  while (n--) {
    u8arr[n] = bstr.charCodeAt(n);
  }
  return new File([u8arr], `${filename}.${suffix}`, {
    type: mime,
  });
};
